In Patmont U.S. Pat. No. 4,821,832, issued Apr. 18, 1989, entitled Motor Scooter Having a Foldable Handle and Friction Drive, I disclosed utilizing the frame of a motor driven scooter as a muffler. Simply stated, such scooters have a forward steered wheel and a rear driven wheel with a structural tube extending therebetween. The structural tube supports a platform. A rider, utilizing an elongated steering handle extending from the steered wheel, stands on the platform and operates controls on the steering handle to a rear wheel driving motor to steer and drive the motorized scooter.
The motor is of a two-cycle variety having a relatively high emission content and a high noise level. In Patmont ""832 it was disclosed to abate the noise level by passing gases from the engine through the tubular structure providing support for the platform between the front steered wheel and the rear driven wheel.
Modern pollution regulations, especially as enforced by The United States Government and the State of California, require pollution abatement from two-cycle engines. Such pollution abatement most conveniently occurs in catalytic converters. Catalytic converters must be heated for optimum catalytic conversion.
Motor driven scooters are a less than optimum location for properly operating catalytic converters. Such operating catalytic converters are hot, frequently operating in the range of about a thousand degrees Fahrenheit. The scooters when operated come into contact with their riders. For example, certain all-terrain scooters are used as both acrobatic and racing machines. In such use, all parts of the scooters come in contact with their riders. If the underside of such a scooter is hot, severe burning of the riding operator or other contestants can easily occur.
A catalytic converter is especially adapted for placement to a motorized scooter. The scooter includes a front steered wheel, a rear driven wheel, and a structural tube extending between the wheels. A motor driving the rear driven wheel has an exhaust emission line. An exhaust tube having first and second open ends is provided. The exhaust tube is mounted through a sidewall of the main structural tube with a first end disposed exterior of the main structural tube and a second end discharging interiorly of the main structural tube. The exhaust tube has a catalytic converter preferably at the second end thereof. A flexible connection is provided between the exhaust emission of the motor and the first end of the exhaust tube. In operation, exhaust flows to heat the catalytic converter concentrically of the main structural tube and the converter operates exothermically at high temperature at the second end of the exhaust tube. Gas passing through the converter expands and cools, typically reverses flow about the exhaust tube, and discharges from the main structural tube. There results optimum catalytic operation, tamperproof location, optimum muffling, and safe heat discharge from the scooter body.